1. Field of the Invention
The present invention relates to an image projecting apparatus for projecting an image onto an exposure position, and more particularly to an image copying apparatus which can be switched between a reader mode in which the image is projected onto a screen for observation and a printer mode in which said image is projected onto an exposure position in scanning motion by means of two scanning mirrors thereby obtaining a copied image.
2. Related Background Art
There is already known a micro reader/printer, which projects a microfilm image in magnified manner on a screen for observation and provides a copied print of said image when necessary.
FIGS. 15 and 16 illustrate an example of the conventional reader/printer, respectively showing the states of an optical system in reader mode and printer mode.
In FIG. 15, the reader/printer contains a lower casing 1, an upper casing 2 and a space portion 3 therebetween.
The lower casing 1 incorporates a film illuminating unit 4 including an illuminating lamp 5, a spherical mirror 6, an illuminating light reflecting mirror 7, a condenser lens 8 etc., and a printer mechanism 9.
Said printer mechanism 9 is comprised of, for example, an electrophotographic copying mechanism including an electrophotographic rotary photosensitive drum 10, a sheet cassette 11, copying sheets 12 contained in said cassette 11, a sheet feeding roller 13, a sheet guide member 14, paired registration rollers 15, a slit plate 16, paired fixing rollers 17, and a discharged sheet tray 18. Around the photosensitive drum, there are provided known image forming process units such as a charger, a developing station, a transfer unit, a cleaning unit etc., though they are omitted from the illustration.
The space portion 3 contains a rolled microfilm guiding mechanism or a microfiche carrier (not shown), a projection lens 19 etc. A microfilm F is set in said roller microfilm guiding mechanism or the microfiche carrier. An image rotating prism 20 is provided at the exit side of the projection lens 19.
The upper casing 2 is provided with a screen 21 at the front side thereof, and contains thereon two reader mirrors 23, 24 for guiding the upward emerging light from said projection (imaging) lens 19 and the prism 20 to the rear face of said screen 21, a movable scanning case 26, and two scanning (printing) mirrors 27, 28 supported mutually rectangularly in said scanning case 26.
In this example, the screen 21 is suspended, rotatably about an axis 22 at the upper edge thereof.
The first reader mirror 23 is fixed, while the second reader mirror 24 is rotatable about a shaft 25.
For scanning exposure of the image, the scanning case 26 is moved, by unrepresented guiding and driving means, in directions a, b (perpendicular to the optical axis from the projection lens 19 to the first fixed reader mirror 23) in the upper casing 2.
In the reader mode state shown in FIG. 15, the scanning case 26 is retained in a home position, behind the second reader mirror 24 at the back of the upper casing 2. The second reader mirror 24 is maintained at an illustrated angular position for reflecting the image bearing light from the first fixed reader mirror 23 to the rear face of the screen 21.
In said reader mode, a desired image frame of the microfilm F, retrieved and positioned above the condenser lens 8 of the film illuminating unit 4, is illuminated from below by said film illuminating unit 4, and the light transmitted by said image frame enters the projection lens 19, then guided through the prism 20, the first reader mirror 23, and the second reader mirror 24 and projected onto the rear face of the screen 21, whereby the magnified image of said image frame of the microfilm is formed on said screen and can be observed from the front side thereof.
The projected image on the screen 21 can be rotated by an arbitrary angle, by the rotation of the prism 20.
For obtaining a copied print of the image projected on the screen 21, an unrepresented print key is actuated whereby the apparatus assumes the printer mode.
More specifically, in response to a print start signal, the printer mechanism 9 is activated, and the scanning case 26 is advanced in a direction a from the home position shown in FIG. 15 to an exposure start position shown by solid lines in FIG. 16. Pushed by the advancing scanning case 26, the second reader mirror 24 rotates clockwise about the shaft 25 and escapes from the path of scanning case 26.
When said scanning case 26 reaches the exposure start position represented by solid lines in FIG. 16, it is reversed in a direction b with a predetermined scanning speed with unrepresented clutch means.
With said reverse displacement of the scanning case 26, the image bearing light emerging from the projection lens 19 and the prism 20 is scanned by the first print mirror 27, and thus scanned light is reflected by the second print mirror 28 and enters the rotary photosensitive drum 10 through the slit of the slit plate 16 of the printer mechanism 9, thereby effecting scanning exposure by the image bearing light on said rotary photosensitive drum 10. Thus the copying operation is conducted by the printer mechanism 9 to provide an enlarged copy of the desired frame of the microfilm F, and said copy is discharged on the tray 18.
The scanning exposure of the image bearing light onto the rotary photosensitive drum 10 is conducted until the scanning case 26 reaches an exposure end position shown by double-dotted chainlines in FIG. 16.
After reaching said exposure end position, the scanning case 26 continues the reverse displacement until it is stopped at the home position shown in FIG. 15.
With the returning of the scanning case 26 to the home position, the second reader mirror 24 is released from its upshifted position caused by said scanning case 26 and returns to the original angular position in the reader mode, shown in FIG. 15.
The direction of the image formed on the sheet 12 can be rotated by an arbitrary angle, by the rotation of the prism 20. Also it is possible to replace the photosensitive drum 10 in the scanning exposure position in the printer mode with a linear image sensor (for example CCD) for photoelectrically reading the image information and to obtain a copy by a laser beam printer based on the output of said image sensor.